Repurposed hexadecimal floating point data path

ABSTRACT

A method includes dividing a fraction of a floating point result into a first portion and a second portion. The method includes outputting a first normalizer result based on the first portion during to a first clock cycle. The method includes storing a first segment of the first portion during to the first clock cycle. The method includes outputting a first rounder result based on the first normalizer result during to the first clock cycle. The method includes outputting a second normalizer result based on the second portion during to a second clock cycle. The method includes outputting a second rounder result based on the second normalizer result and the first segment during to the second clock cycle.

BACKGROUND

The present invention relates to a repurposed hexadecimal floating pointdata path, and more specifically, to use of the hexadecimal data buswith different floating point number formats.

SUMMARY

Embodiments may include methods, systems, and circuitry for hexadecimalextended precision data buses. A method includes dividing a fraction ofa floating point result into a first portion and a second portion. Themethod includes outputting a first normalizer result based on the firstportion during to a first clock cycle. The method includes storing afirst segment of the first portion during to the first clock cycle. Themethod includes outputting a first rounder result based on the firstnormalizer result during to the first clock cycle. The method includesoutputting a second normalizer result based on the second portion duringto a second clock cycle. The method includes outputting a second rounderresult based on the second normalizer result and the first segmentduring to the second clock cycle.

A floating point unit includes hexadecimal floating point normalizercircuitry including a result register sized to output a normalizedhexadecimal result that includes a first segment and a second segment.The floating point unit includes latch circuitry having a bit widthsized to retain the first segment of the normalized hexadecimal resultas buffered data. The floating point unit includes hexadecimal floatingpoint rounder circuitry having an input register bit width sized toreceive the first segment and the second segment from the hexadecimalfloating point normalizer circuitry and the buffered data from the latchcircuitry.

A floating point unit includes hexadecimal floating point normalizercircuitry. The hexadecimal floating point normalizer circuitry includesan input register sized to receive a first portion of a fraction portionof a floating point number and a second portion of the fraction portionof the floating point number. The hexadecimal floating point normalizercircuitry includes a result register sized to output a normalizedhexadecimal result that includes a first segment and a second segment,the output based on the fraction portion. The floating point unitincludes latch circuitry having a bit width sized to retain the firstsegment associated with the first portion of the normalized hexadecimalresult as buffered data. The floating point unit includes hexadecimalfloating point rounder circuitry. The hexadecimal floating point roundercircuitry includes an input register bit width sized to receive thefirst segment and the second segment associated with the second portionof the normalized hexadecimal result from the hexadecimal floating pointnormalizer circuitry, and the buffered data from the latch circuitry.

Additional technical features and benefits are realized through thetechniques of the present invention. Embodiments and aspects of theinvention are described in detail herein and are considered a part ofthe claimed subject matter. For a better understanding, refer to thedetailed description and to the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The subject matter which is regarded as the invention is particularlypointed out and distinctly claimed in the claims at the conclusion ofthe specification. The forgoing and other features, and advantages ofthe invention are apparent from the following detailed description takenin conjunction with the accompanying drawings in which:

FIG. 1 illustrates a block diagram of portions of a floating point unithaving circuitry in accordance with one or more embodiments of thepresent invention;

FIG. 2A illustrates a double precision hexadecimal floating point numberin accordance with one or more embodiments of the present invention;

FIG. 2B illustrates an quadruple precision binary floating point numberin accordance with one or more embodiments of the present invention; and

FIG. 3 illustrates a method for using hexadecimal circuitry to processquadruple precision binary floating point numbers in accordance with oneor more embodiments of the present invention.

DETAILED DESCRIPTION

Floating point numbers are defined by various formats. Floating pointexecution units are often repurposed to perform operations on particularfloating point number formats. As the precision of floating pointnumbers is increased, additional clock cycles may be used to completeoperations. The additional clock cycles typically underutilize existingdata paths associated with the respective floating point number formatsand aggravate critical path execution processing time. Floating pointexecution units associated with different floating point formats may berepurposed to process such increased precision formats that may reducethe clock cycles, power, and/or hardware required.

A critical path includes a group of functional operations and clockcycle requirements to obtain a desired result. Each functional operationon the critical path often increases the processing time for anoperation or process to complete. Precision for floating point unitsrelates to the amount of detail encapsulated in the binary number. Forexample, precision thresholds may include single precision (32 bits),double precision (64 bits), quadruple precision (128 bits) or any othernumber of associated bits. Normalization of floating point numbersarranges the fractional portion of the number to remove the leadingzeros of the floating point format and adjusts the exponent accordingly.Floating point numbers with increased precision or precision greaterthan the normalizer bus bit width typically require additionalnormalization cycles to properly normalize the extended precisionnumber. For example, a double precision number may be normalized on asingle precision normalizer. As such, additional clock cycles may berequired for a residue check to be completed. A quadruple precisionnumber may be normalized on a single or double precision normalizer. Thefloating point number may be a binary floating point number or ahexadecimal floating point number.

Embodiments described herein provide operations of a floating pointunit. It should be appreciated that any arithmetic unit, floating pointor otherwise, may implement teachings described herein or portionsthereof. Circuitry refers to any combination of logic, wires,fundamental components, transistors, diodes, latches, switches,flip-flops, or other implements, that may be arranged to carry theintended output or disclosed operations. It should be appreciated thatthe term register may not refer to memory retention and merely includedata or signal passthrough.

A rounder or rounder circuitry may receive normalizer output andproperly define the receive floating point number to the correct numberof significant digits or otherwise. Extended precision operations mayperform rounding in multiple clock cycles. That is, the floating pointunit may be operated according to a clock or pulse indication, directingthe floating point unit to process the next set of information. Theclock is typically defined by any oscillator or oscillating signal. Assuch, portions of the floating point number fraction are often processedby the rounder circuitry according to discrete clock cycles to providerounding result output from the floating point unit. Result registersmay be preconfigured to receive rounder circuitry output in the form ofpredetermined portions of the floating point number. Clock-basedoperations may be performed according to any number of clock cyclesperformed consecutively or intermittently.

Referring to FIG. 1, a floating point unit 100 is shown in accordancewith one or more embodiments of the present invention. Floating pointunit 100 receives a first operand 102 and a second operand 104. Thefloating point unit 100 may include an adder 106 or circuitry to performanother arithmetic operation on the first operand 102 and the secondoperand 104. It should be appreciated that any number of arithmeticoperations may be performed on the first operand 102 and the secondoperand 104. Any number of additional operands may further be used. Thehexadecimal floating point normalizer circuitry 108 shown in FIG. 1normalizes a decimal position associated with the floating point numberreceived from adder 106.

The hexadecimal normalizer circuitry 108 may be a double precisionhexadecimal floating point normalizer or a hexadecimal floating pointnormalizer circuitry and include an input register 107 and a resultregister 109. The normalized hexadecimal result register 109 is sized tooutput a hexadecimal result. For extended floating point numbers such asquadruple precision numbers, the hexadecimal normalizer circuitry 108shown in FIG. 1 outputs a normalized fraction portion of the quadrupleprecision number in accordance with one or more embodiments of thepresent invention. The result register 109 is sized to output anormalized hexadecimal result, where the normalized hexadecimal resultis the fraction portion of a floating point number or a portion of thefraction portion. As an example, during a first clock cycle the resultregister 109 outputs a first portion of the fraction portion of thefloating point number normalized by the hexadecimal floating pointnormalizer circuitry 108 in accordance with one or more embodiments. Theresult register 109 may output to a bus 110 having a bit width of 57bits for the typical 56-bit hexadecimal fraction plus a leading zero toolarge bit. The 56-bit hexadecimal fraction may be split into a firstsegment and a second segment. The first segment may be an 8-bit segmentand the second segment may be a 49-bit segment. The bus 110 connects theresult register 109 of the hexadecimal floating point normalizercircuitry 108 to the hexadecimal floating point rounder circuitry 112input register 111. Input register 111 has a bit width, or acceptedamount of bits, similar to the bus 110.

The hexadecimal floating point rounder circuitry 112 may be a doubleprecision hexadecimal floating point rounder that may round the receivedfraction portion to from bus 110 to the required amount. The hexadecimalfloating point rounder circuitry 112 computes the rounded result andoutputs to output register 113. The output register 113 is associatedwith a result bus 114 that provides the hexadecimal floating pointrounder circuitry 112 result to result circuitry 116. Result circuitry116 may be used by a processor or other circuitry to use or display thecalculated floating point number. The result circuitry 116 may havepredetermined bit width inputs. For example, the result circuitry 116may anticipate rounder outputs to have a 48-bit width during the firstcycle and a 64-bit width during the second cycle. That is, the outputregister 113 may have a 64-bit width configured to output a 48-bitresult and a 64-bit result depending on the clock cycle.

The floating point unit 100 shown in FIG. 1 includes latch circuitry 120having a bit width sized to retain the first segment of the firstportion of the floating point number in accordance with one or moreembodiments of the present invention. The first segment may be stored asbuffered data or defined as buffered data with registers of the latchcircuitry 120. The latch circuitry 120 may include a supply bus 118having a bit width sized to supply the first segment to the latchcircuitry 120. The supply bus 118 may be disposed before or after thehexadecimal floating point rounder circuitry 112. The bit width of thelatch circuitry may be eight bits for double precision hexadecimalfloating point data paths that are processing quadruple precisionfloating point numbers. During the first processing cycle the firstsegment is stored in the latch circuitry 120 and the hexadecimalfloating point rounder circuitry 112 provides the rounded second segmentassociated with the first portion in output register 113. During thesecond processing cycle the latch circuitry 120 releases the storedfirst segment as buffered data to the input register 111 of thehexadecimal floating point rounder circuitry 112. The input register 111of the hexadecimal floating point rounder circuitry 112 receives thesecond portion of the fraction portion of the floating point number frombus 110 and combines the second portion with the buffered data such thatthe hexadecimal floating point rounder circuitry 112 outputs the 64-bitsecond cycle result to the result circuitry 116. As such, through twoclock cycles of the floating point unit, the result register 116 firstreceives the 48-bit fraction rounder result from result bus 114 and thenreceives the 64-bit rounder result from bus 114.

Referring to FIG. 2A, a double extended precision hexadecimal floatingpoint number 200 is shown. The double extended precision hexadecimalfloating point number 200 includes an extended precision sign bit 202.The double extended precision hexadecimal floating point number 200includes extended precision hexadecimal exponent bits 204 having a bitwidth of seven bits. The extended precision hexadecimal precisionfloating point number 200 includes extended precision hexadecimalfraction bits 206 having a bit width of 56 bits.

Referring to FIG. 2B, a quadruple precision floating point number 210 isshown. The quadruple precision floating point number 210 may be aquadruple precision binary floating point number or another binaryfloating point number. The quadruple precision floating point number 210includes a quadruple precision sign bit 212. The quadruple precisionfloating point number 210 includes quadruple precision exponent bits 214having a bit width of fifteen bits. The quadruple precision floatingpoint number 210 includes 112 quadruple precision fraction bits 216. Thefraction portion 216 may include a first portion 230 and a secondportion 232. The fraction portion 216 may be split in half to form thefirst portion 230 and the second portion 232. That is, the first portion230 may include 56 bits and the second portion 232 may include 56 bits.The first portion 230 may include an additional leading zero too largebit or one bit leading zero too large flag, defining an anticipatedleading zero control signal, making the first portion 230 57 bits. Theleading zero too large bit may be used as an indication of thehexadecimal normalizer circuitry 108 control instructions used tonormalize the floating point number. The second portion 232 may includean additional leading zero too large bit, making the second portion 23257 bits. As such, the quadruple precision floating point number 210 maybe processed by the hexadecimal floating point rounder circuitry 112 intwo clock cycles. The first portion 230 defines a first segment 234 anda second segment 236. The first segment 234 is stored in the latchcircuitry 120 during a first cycle of the floating point unit 100 inaccordance with one or more embodiments of the present invention. Thefirst segment 234 may be eight bits. It should be appreciated that firstportion 230, second portion 232, first segment 234, and second segment236 are designations of bits or bit groupings. The groupings may be inany order, out of order, rearranged, or interchanged.

Referring to FIG. 3, a method 300 is shown in accordance with portionsof one or more embodiments of the present invention. The method 300begins in block 302. It should be appreciated that any of the blocks ofmethod 300 may be omitted, repeated, rearranged, and any of the blocksof method 300 may be completed in sequence or in parallel. In block 304,hexadecimal floating point normalizer circuitry 108 of the floatingpoint unit 100 receives a floating point result. In block 306, thefloating point result is analyzed to determine whether the floatingpoint result is a hexadecimal floating point number 200 or a binaryfloating point number 210. If the result is not a hexadecimal floatingpoint number 200, the standard data path for that type may be used inblock 307. The floating point result may be analyzed by the hexadecimalnormalizer circuitry 108 or another processor and circuitry associatedwith the floating point unit 100. If the floating point result is abinary floating point number 210, the floating point unit 100 mayreceive the fraction portion 216 of the floating point number 210 inblock 308.

At block 310, the fraction portion 216 is portioned or divided accordingto a bit width of bus 110. The hexadecimal normalizer circuitry 108 mayportion or divide the fraction portion 216 during normalization or thefraction portion 216 may be multiplexed or otherwise divided orportioned with additional circuitry. The bit width of bus 110 may be 57bits sized as necessary to accommodate the 57 bit fraction portion 206of hexadecimal floating point numbers 200. As such, the fraction portion216 may be separated for example into a first portion 230 of 57 bits anda second portion 232 of 57 bits. The hexadecimal floating pointnormalizer circuitry 108 outputs the normalizer result through resultregister 109 and bus 110 based on the first portion 230 in block 312. Afirst segment 234 of the hexadecimal floating point normalizer circuitry108 result is stored in latch circuitry 120 in block 314. The secondsegment 236 may be rounded according to hexadecimal floating pointrounder circuitry 112 in block 316. The first rounder result may beoutputted based on the first normalizer result. That is, the firstrounder result (48 bits) based on the second segment 236 of the firstportion 230 may be sent to result circuitry 116 during a first clockcycle or according to a first clock cycle of the floating point unit.

In block 318, the second normalizer result is outputted from resultregister 109 to bus 110. The second normalizer result may be based onthe second portion 232. In block 320, the hexadecimal floating pointrounder circuitry 112 may output a second rounder result based on thesecond normalizer result and the buffered data stored in the latchcircuitry 120 according to the first segment 234. In block 322, thefirst rounder result and the second rounder result, based on the firstportion 230 and the second portion 232 may be combined to form thequadruple precision floating point number originally desired by thecombination of operand 102 and operand 104.

The clock cycles, hardware, and/or power required to normalize and roundincreased precision floating point numbers by the floating point unit100 may be reduced while maintaining anticipated hexadecimal floatingpoint rounder circuitry 112 output by storing portions or segments ofthe floating point number.

It should be appreciated that any number of clock cycles, intermediateor otherwise, may be implemented to provide similar results. The numberformats discussed and disclosed may be scaled according to any necessaryprecision. As an example, the quadruple precision floating point number210 may be an octuple precision floating point number and the doubleextended precision hexadecimal floating point number 200 may be aquadruple extended precision hexadecimal floating point number. As such,the associated circuitry may similarly scale.

Various embodiments of the invention are described herein with referenceto the related drawings. Alternative embodiments of the invention can bedevised without departing from the scope of this invention. Variousconnections and positional relationships (e.g., over, below, adjacent,etc.) are set forth between elements in the following description and inthe drawings. These connections and/or positional relationships, unlessspecified otherwise, can be direct or indirect, and the presentinvention is not intended to be limiting in this respect. Accordingly, acoupling of entities can refer to either a direct or an indirectcoupling, and a positional relationship between entities can be a director indirect positional relationship. Moreover, the various tasks andprocess steps described herein can be incorporated into a morecomprehensive procedure or process having additional steps orfunctionality not described in detail herein.

In an exemplary embodiment, the methods described herein can beimplemented with any or a combination of the following technologies,which are each well known in the art: a discrete logic circuit(s) havinglogic gates for implementing logic functions upon data signals, anapplication specific integrated circuit (ASIC) having appropriatecombinational logic gates, a programmable gate array(s) (PGA), a fieldprogrammable gate array (FPGA), etc.

Additionally, the term “exemplary” is used herein to mean “serving as anexample, instance or illustration.” Any embodiment or design describedherein as “exemplary” is not necessarily to be construed as preferred oradvantageous over other embodiments or designs. The terms “at least one”and “one or more” may be understood to include any integer numbergreater than or equal to one, i.e. one, two, three, four, etc. The terms“a plurality” may be understood to include any integer number greaterthan or equal to two, i.e. two, three, four, five, etc. The term“connection” may include both an indirect “connection” and a direct“connection.”

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting of the invention. Asused herein, the singular forms “a”, “an” and “the” are intended toinclude the plural forms as well, unless the context clearly indicatesotherwise. It will be further understood that the terms “comprises”and/or “comprising,” when used in this specification, specify thepresence of stated features, integers, steps, operations, elements,and/or components, but do not preclude the presence or addition of oneor more other features, integers, steps, operations, elements,components, and/or groups thereof.

The corresponding structures, materials, acts, and equivalents of allmeans or step plus function elements in the claims below are intended toinclude any structure, material, or act for performing the function incombination with other claimed elements as specifically claimed. Thedescription of the present invention has been presented for purposes ofillustration and description, but is not intended to be exhaustive orlimited to the invention in the form disclosed. Many modifications andvariations will be apparent to those of ordinary skill in the artwithout departing from the scope and spirit of the invention. Theembodiments were chosen and described in order to best explain theprinciples of the invention and the practical application, and to enableothers of ordinary skill in the art to understand the invention forvarious embodiments with various modifications as are suited to theparticular use contemplated.

Aspects of the present invention are described herein with reference toflowchart illustrations and/or block diagrams of methods, apparatus(systems), and computer program products according to embodiments of theinvention. It will be understood that each block of the flowchartillustrations and/or block diagrams, and combinations of blocks in theflowchart illustrations and/or block diagrams, can be implemented bycomputer readable program instructions.

The instructions disclosed herein, which may execute on the computer,other programmable apparatus, or other device implement thefunctions/acts specified in the flowchart and/or block diagram block orblocks.

The flowchart and block diagrams in the Figures illustrate thearchitecture, functionality, and operation of possible implementationsof systems, methods, and computer program products according to variousembodiments of the present invention. In this regard, each block in theflowchart or block diagrams may represent a module, segment, or portionof instructions, which comprises one or more executable instructions forimplementing the specified logical function(s). In some alternativeimplementations, the functions noted in the blocks may occur out of theorder noted in the Figures. For example, two blocks shown in successionmay, in fact, be executed substantially concurrently, or the blocks maysometimes be executed in the reverse order, depending upon thefunctionality involved. It will also be noted that each block of theblock diagrams and/or flowchart illustration, and combinations of blocksin the block diagrams and/or flowchart illustration, can be implementedby special purpose hardware-based systems that perform the specifiedfunctions or acts or carry out combinations of special purpose hardwareand computer instructions.

The descriptions of the various embodiments of the present inventionhave been presented for purposes of illustration, but are not intendedto be exhaustive or limited to the embodiments disclosed. Manymodifications and variations will be apparent to those of ordinary skillin the art without departing from the scope and spirit of the describedembodiments. The terminology used herein was chosen to best explain theprinciples of the embodiments, the practical application or technicalimprovement over technologies found in the marketplace, or to enableothers of ordinary skill in the art to understand the embodimentsdisclosed herein.

What is claimed is:
 1. A floating point unit comprising: hexadecimalfloating point normalizer circuitry configured to output a normalizedhexadecimal result that includes a first segment and a second segment,including a result register sized to the normalized hexadecimal result;latch circuitry configured to retain the first segment of the normalizedhexadecimal result as buffered data, the latch circuitry having a bitwidth sized to the first segment; and hexadecimal floating point roundercircuitry configured to output a rounded result and having an inputregister configured to receive the first segment and the second segmentfrom the hexadecimal floating point normalizer circuitry and thebuffered data from the latch circuitry, the input register having a bitwidth sized to the first segment and the second segment.
 2. The floatingpoint unit of claim 1, wherein the hexadecimal floating point normalizercircuitry further includes an input register sized to receive a firstportion of a fraction of a floating point result.
 3. The floating pointunit of claim 2, wherein the floating point result is quadrupleprecision.
 4. The floating point unit of claim 2, wherein the firstportion includes a first half of the fraction.
 5. The floating pointunit of claim 4, wherein the fraction is 112 bits.
 6. The floating pointunit of claim 4, wherein the first portion includes a leading zeroanticipator too large bit configured to denote error in an anticipatedleading zero control signal associated with the hexadecimal floatingpoint normalizer circuitry.
 7. A floating point unit comprising:hexadecimal floating point normalizer circuitry configured to output anormalized hexadecimal result that includes a first segment and a secondsegment, including: an input register sized to receive a first portionof a fraction portion of a floating point number and a second portion ofthe fraction portion of the floating point number; and a result registersized to output the normalized hexadecimal result, the output based onthe fraction portion; latch circuitry configured to retain the firstsegment associated with the first portion of the normalized hexadecimalresult as buffered data, the latch circuitry having a bit width sized tothe first segment; and hexadecimal floating point rounder circuitryconfigured to output a rounded result, including: an input registerconfigured to receive the first segment and the second segmentassociated with the second portion of the normalized hexadecimal resultfrom the hexadecimal floating point normalizer circuitry and thebuffered data from the latch circuitry, and having a bit width sized tothe first segment and the second segment.
 8. The floating point unit ofclaim 7, wherein the first portion is a first half of the fractionportion.